1. Field of the Invention
The present invention relates in general to electronic assemblies and the testing thereof. More specifically, the present invention relates to a method and apparatus for the transport and handling of die from an original wafer to a test board, a printed circuit board, and/or a final product substrate.
2. Description of Related Art
The subject of chip scale packaging has been the focus of intense study in the industry for many years. One very promising technology involves securing small, resilient members onto a suitable substrate and using these members to effect contact between an active device and other circuitry. Methods are known for making such resilient interconnection elements used for microelectronics, and for fabricating spring contact elements directly on semiconductor devices. A particularly useful resilient interconnection element comprises a free standing spring contact element secured at one end to an electronic device and having a free end standing away from the electronic device so as to readily contact a second electronic device. See, for example, U.S. Pat. No. 5,476,211, entitled “Method for Manufacturing Electrical Contacts, Using a Sacrificial Member.”
A semiconductor device having spring contact elements mounted thereto is termed a springed semiconductor device. A springed semiconductor device may be interconnected to an interconnection substrate in one of two principal ways. It may be permanently connected, such as by soldering the free ends of the spring contact elements to corresponding terminals on an interconnection substrate such as a printed circuit board. Alternatively, it may be reversibly connected to the terminals simply by urging the springed semiconductor device against the interconnection substrate so that a pressure connection is made between the terminals and contact portions of the spring contact elements. Such a reversible pressure connection can be described as self-socketing for the springed semiconductor device. A discussion of making semiconductors with spring packaging (MicroSpring™ contacts) is found in U.S. Pat. No. 5,829,128, issued Nov. 3, 1998, entitled “Method of Mounting Resilient Contact Structures to Semiconductor Devices.” A discussion of using and testing semiconductors with MicroSpring™ contacts is disclosed in U.S. patent application Ser. No. 09/205,502, filed Dec. 4, 1998, entitled “Socket for Mating with Electronic Component, Particularly Semiconductor Device with Spring Packaging, for Fixturing, Testing, Burning-In or Operating Such a Component”, and assigned to the assignee of the present invention.
The ability to remove a springed semiconductor device from a pressure connection with an interconnection substrate would be useful in the context of replacing or upgrading the springed semiconductor device. A very useful object is achieved simply by making reversible connections to a springed semiconductor device. This is also useful for mounting, temporarily or permanently, to an interconnection substrate of a system to burn-in the springed semiconductor device or to ascertain whether the springed semiconductor device is measuring up to its specifications. As a general proposition, this can be accomplished by making pressure connections with the spring contact elements. Such contact may have relaxed constraints on contact force and the like.
In a typical manufacturing process, a wafer is subjected to limited testing to identify gross functionality or non-functionality of individual components on the wafer. The functional individual semiconductor components or die are then packaged for further burn-in and more comprehensive testing. The packaging process is both expensive and time consuming.
Using the MicroSpring contacts for interconnects provides fully testable die while still on the wafer. One preferred method of testing the die is to singulate them, then move them through a more or less typical test flow as is currently performed on packaged devices. A key difference is that the die are already packaged once singulated from the wafer, but current testing equipment is not adapted for use with such devices.
To achieve this, a chip level part or IC die could be placed into a carrier once it is diced from the original wafer. The carrier could then transport the die to the test board for burn-in tests, for example. Once all die in the carrier pass inspection, the carrier could then be used to transport and mount the die onto the printed circuit board or final product substrate.
Such a carrier would be particularly useful for die which include MicroSpring contacts, or similar contacts. Such a carrier also would be useful for traditional die for making contact with a test apparatus or final product that includes a suitable connection mechanism. A test apparatus or final product including MicroSpring contacts would be particularly useful for connecting to traditional die.
A chip level carrier would provide several advantages over the art. First, an individual die would be tested and could be replaced if it failed testing. Second, a chip level carrier could incorporate a tracking mechanism that could track each individual die, storing relevant information on the carrier for monitoring and tracking. Third, a chip level carrier allows for easy handling of numerous dies and protects the dies and their spring contacts during transportation, storage and use. Further, a carrier could limit the amount of compression the spring contacts on the die under test underwent, which may be less than the compression allowed during subsequent primary use of the die. The limitation of the compression could be achieved through design decisions to determine a maximum allowable compression for the spring contacts during the testing phase. Then, different limits can be adopted for actual use. This feature would increase the “travel” life of the spring.